 function [phi,phi_x,phi_y,phi_xx,phi_xy,phi_yy] = fe_Hermit(x ,y)  
% function [phi,phi_x,phi_y,phi_xx,phi_xy,phi_yy] = fe_Hermit(x ,y)  
% The evaluation of cubic hermit elements on triangle
%
%    x and y is the corresponding value of L1 and L2 
%    3
%    |  \
%    |    \
%    |      \
%    1 ------ 2
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

phi(:,1) = (1 - x - y).*(1 + x + y - 2*x.*x - 11*x.*y - 2*y.*y);
phi(:,2) = x.*(1 - x - y).*(1 - x - 2*y);
phi(:,3) = y.*(1 - x - y).*(1 - 2*x - y);
phi(:,4) = -2*x.*x.*x + 7*x.*x.*y + 7*x.*y.*y + 3*x.*x - 7*x.*y;
phi(:,5) = x.*y.*(2*x + y - 1);
phi(:,6) = 7*x.*x.*y + 7*x.*y.*y - 2*y.*y.*y + 3*y.*y - 7*x.*y;
phi(:,7) = x.*y.*(x + 2*y - 1);
phi(:,8) = y.*y.*y - 2*y.*y.*x - 2*y.*x.*x - y.*y + 2*x.*y;
phi(:,9) = 27*x.*y.*(1 - x - y);

